Could be any number of things - ground hog, deer, raccoons, rabbits, squirrels, woodchuck, turtles, mice, slugs, etc. especially if the garden isn't fenced. It all depends on what kinds of wildlife you have in your area.

Unfortunately you are the only one that can monitor your garden and ID the culprit. All we can do is guess. Not much help I know but you must have some idea of what kinds of wildlife you commonly see in your area?

To save the remaining ones you will have to enclose them in some fashion so none of the above can get to them - cages or fencing, chicken wire dome, etc.

Dave

I'm in the middle of the city. No wildlife to speak of besides the occasional bird. Maybe slugs. We've had a ton of rain and I picked a good dozen out of the potato patch.